I thought that IB charged a fee based on the fee established by the Option Exchange where the order rested. I'm rather certain that there is no fee for a day order that expires unfilled.
they charged me twice, $1.5 each time. I'm too lazy right now to log onto my account to get the printscreen. they also logged me off very often, then I had to log back in again and again, then website said either my password or username or the "PKI" keys are not valid.... st00pid website. I've been quite frustrating with their setup. Even though TD Ameritrade charges little more $34 for round trip, but I've never had problem with their website... IB charged me $24 dollars for closing out my puts today. I thought I can save money with IB, apparently not.
Don't know about the charges but the server will log you off if your internet connection goes down for any length of time. Have you had any internet problems? The PKI message sounds like some form of internet problem. TWS will work through short-duration data losses and reconnect without the need to go thru a manual login. Another possible reason, but it doesn't explain the PKI message - TWS will log you off once a day unless you reset the logoff time each day. If you are not familar with the feature, go to "Configure", then select "Lock and Exit." You'll have to reset the time each day if you keep your TWS on 24 hours. Or just set it for the middle of the night when you are normally shutdown for the day. I'd give support a call or open a trouble ticket with the exact working of the error message. Jack